JP2911341B2 - Printer control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer control device used for a printer device which requires resolution conversion or enlargement / reduction of image data.

[0002]

2. Description of the Related Art Conventionally, in a facsimile apparatus for transmitting text, drawings, and the like, a received image is recorded on a thermal recording paper using a thermal head. A plain paper facsimile apparatus for recording on plain paper using a photographic method has attracted attention. On the other hand, as a printer using an electrophotographic method, a printer used for a personal computer or the like has been put to practical use in advance. Therefore, it is conceivable to use such a printer as a printing device of a facsimile machine.

However, in this case, the printing resolution of the printer is 240 dpi (dot per i).
nchi) and 300 dpi are common, and do not match the resolution of the main scanning 8 pixels / mm, the sub-scanning 7.7 pixels / mm, or the sub-scanning 3.85 pixels / mm used in the facsimile machine. Therefore, a resolution conversion process for matching these is required.

In a plain paper facsimile machine, printing is usually performed using cut paper. In this case, even if the size of the original document on the transmitting side and the size of the cut sheet on the receiving side are the same, the transmission side uses communication history information called a header added by the transmitting side. In some cases, the length of one page becomes longer and printing on one page cannot be performed.
In such a case, printing is performed over two pages, and the second page uses only a portion of about a few centimeters at the beginning, thus not only increasing waste, but also causing the content of the document to be cut off in the middle. Hard to read. For this reason, the plain paper facsimile apparatus performs a process of reducing a received image so as to fit on one page.

[0005]

However, since the above-mentioned reduction processing is performed by a simple thinning method, there are disadvantages that thin lines are lost or legibility is reduced. In addition, resolution conversion is performed by the nearest neighbor method, and there is a problem that image quality is degraded due to occurrence of moire in a halftone image.

The present invention has been made in view of the above circumstances, and has as its object to provide a printer control apparatus capable of suppressing a decrease in image quality due to resolution conversion and enlargement / reduction.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a printer control device according to the present invention includes a line buffer for storing and holding input image data, and a single print line image formed of a plurality of sub-line images. Exposure means formed by a plurality of exposures based on data, and a plurality of sub-lines divided in the sub-scanning direction constitute one print line, and a main line is formed based on image data of the print line stored in the line buffer. Resolution conversion rate or enlargement /
A plurality of sub-line image data in which sampling positions are different from each other when performing sampling in accordance with the reduction conversion rate, and a main-scanning direction resolution or the like conversion unit for sequentially supplying each sub-line image data to the exposure unit; , Are provided.

[0008]

According to the above construction, one print line is composed of, for example, four sub-lines, and sample positions for generating each sub-line image data are different from each other in resolution conversion and enlargement / reduction in the main scanning direction. In the conventional resolution conversion or the like, variations occur in units of sublines, for example, where one pixel after resolution conversion becomes all black pixels, for example, only two sublines out of four sublines in one pixel after resolution conversion become black. This can suppress the occurrence of moire in the halftone image.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing the embodiments. FIG. 1 is a block diagram schematically showing a printer control apparatus, in which 1 is an image input unit, 2 is a line buffer, 3 is an exposure control unit, 4 is a resolution conversion unit, and 5 is a line head. The line head 5 and the exposure control means 3 constitute an exposure means.

An image input unit 1 takes in an externally input raster-scanned image and writes one line of image data into a line buffer 2. In the case of a facsimile apparatus, received image data is written from the image input unit 1 to the line buffer 2.

The line buffer 2 has a storage capacity for two lines. These two lines include a print line and a line after the print line. A line after the print line (hereinafter, referred to as a rear line) is a line written from the image input unit 1, and the print line is a line head 5.
Is a readout line supplied to the readout line.

The resolution conversion means 4 generates an address at which the print line image data is stored, and supplies the generated address to the line buffer 2. As a result, the print line image data is read from the line buffer 2. The reading of the image data is repeated the same number of times as the number of line divisions (4 in this embodiment) within the time for writing the image data of the subsequent line.
The read image data of the print line is supplied to the line head 5 as sub-line image data. At this time, resolution conversion and enlargement / reduction processing are performed.

Specifically, the resolution conversion and the like are as follows: a) In the case of resolution conversion in the main scanning direction The input image data is sampled at a frequency corresponding to the resolution conversion rate. The sample positions are different from each other depending on the number of the subline).

(B) In the case of enlargement / reduction in the main scanning direction Similarly, input image data is sampled at a frequency corresponding to an enlargement ratio or a reduction ratio. The sample positions differ from each other.

The above processing is an example, and the present invention is not limited to this.

The exposure control means 3 sets the number of exposures equal to the number of repetitions of reading image data (the number of divided lines) to one
This is performed for a print line. At each exposure, information indicating the number of times is output to the resolution conversion unit 4 so that subline image data corresponding to the number of times is generated, and the subline image is output. The line head 5 is driven (lighting control) based on the data.

The line head 5 includes a shift register 6, a line buffer 7, and a light emitting section 8. The sub-line image data subjected to the resolution conversion and the like is stored in the shift register 6. When one sub-line image data is stored in the shift register 6, the image data is simultaneously transferred to the line buffer 7. Then, the light emitting section 8 of the line head 5 is turned on based on the image data of the line buffer 7. This lighting is the original one
This is 1/4 of the lighting time for the line. In other words, while one line of image input is being performed, four sub-line image data are sequentially supplied to the line head 5, and the light emitting section 8 of the line head 5 generates four lighting patterns.

The size of the light-emitting elements constituting the light-emitting section 8 does not necessarily have to be reduced in the sub-scanning direction in accordance with the number of sub-line divisions. I just need. That is, the size of the light emitting element may be a normal size, and the light emitting element may be configured to emit light four times while the photosensitive member rotates by one line.

Next, the operation of the printer control device will be described with reference to FIG. FIG. 2 shows the resolution conversion in the main scanning direction. FIG. 2A is a conceptual diagram showing the lighting state of the light emitting unit 8 in the line head 5 for each subline after resolution conversion for facsimile image data. .
FIG. 2B is a time chart showing facsimile image data, and FIGS. 2C to 2F are time charts showing sample timing signals of each subline.

In FIG. 2, one line is formed by a plurality of sub-lines. The sub-line is obtained by dividing one line in the sub-scanning direction by the number of repetitions. In this embodiment, the number of sub-lines is four as described above. Here, as shown in this figure, the II-th pixel and the III-th pixel in the image data after the resolution conversion for the facsimile image data in the same figure (b), all of the four sub-lines are white or black pixels. Instead, variations occur. This is because the sample timing signals in the first to fourth sub-line image data generation correspond to (c) to (f) in FIG.
This is because the sample positions are different from each other as shown in FIG. FIG. 3 simply shows sample positions of the first to fourth sublines.

The four sub-line image data of one line generated in this manner are
Supplied to Since the light emission of the light emitting unit 8 of the line head 5 is controlled in accordance with the sub-line image data, for example, in the case of the second pixel, the minute light-emitting units corresponding to the first, second, and third sub-lines are turned off, and The minute light emitting section corresponding to the sub line is turned on.

As described above, one print line is set to, for example, 4
In the resolution conversion in the main scanning direction based on the image data of the print line, the sample positions at the time of generating each sub-line image data are made different from each other. FIG. 2 shows that all the one pixel (the II-th pixel and the III-th pixel) after resolution conversion becomes a black pixel (the sample position is the center), as shown in FIG. For example, it is possible to suppress the occurrence of moiré in a halftone image by causing variations in subline units, for example, only two sublines become black.

The same applies to the case of enlargement / reduction in the main scanning direction. Sampling is performed at a frequency corresponding to the enlargement ratio or reduction ratio, and the facsimile is performed by changing the sample positions for each subline at this time. The image quality is improved by sampling the image data.

In the resolution conversion and enlargement / reduction in the sub-scanning direction, the lighting time of each light emitting element in the light emitting section 8 and the rotation speed of the photosensitive member may be adjusted.

In this embodiment, the number of repetitions (the number of sub-lines) is set to 4. However, by increasing the number of repetitions, the moire reduction performance can be improved. However, since reading from the line buffer 2 and storing data in the line head 5 are frequently performed, the number of sub-lines is determined in consideration of the balance between them.

[0026]

As described above, according to the present invention, in a printer device which requires resolution conversion or enlargement / reduction of image data, the occurrence of moire or the like is suppressed to improve the image quality. It has the effect of being able to do so.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a printer control device of the present invention.

FIG. 2 is a conceptual diagram illustrating a lighting state of a line head when performing resolution conversion in a main scanning line direction according to the present invention, and a timing chart illustrating timing signals and the like of each sub line.

FIG. 3 is an explanatory diagram showing a sample position of each sub line according to the present invention in relation to pixels after resolution conversion.

FIG. 4 is a conceptual diagram showing a line head lighting state in a case where resolution conversion is performed in the conventional main scanning line direction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image input part 2 Line buffer 3 Exposure control means 4 Resolution conversion means 5 Line head 6 Shift register 7 Line buffer 8 Light emitting part

Claims (1)

(57) [Claims] A line buffer configured to store input image data; an exposure unit configured to form one print line image by a plurality of exposures based on a plurality of subline image data; A plurality of sub-lines constitute one print line, and sampling is performed according to a resolution conversion rate or an enlargement / reduction conversion rate in the main scanning direction based on image data of a print line stored in the line buffer. A printer control device for generating a plurality of sub-line image data having different sample positions from each other, and a main-scanning-direction resolution conversion means for sequentially supplying each sub-line image data to the exposure means.